SQUARE WALLET, an innovative new app, is changing the way we spend our money. Here’s how it works: you link your credit or debit card to the app, shop, take your items to a cashier at a participating retailer and, as the company’s Web site says, “simply say your name at checkout to pay.” Your name and photograph appear on the register, the cashier gives you a nod, and you walk happily out the door with your artisan shade-grown organic coffee.

This kind of seamless convenience has obvious benefits. But it may come with hidden costs. The iPad (which placed ahead of world peace in a 2011 poll of what people might wish for) and other electronics make it possible for us to get movies, games and books the moment we want them and to worry about the money later. It’s a payment system that encourages instant gratification. Interestingly, however, research suggests that we derive greater happiness from goods we pay for immediately, but don’t use for some time, than we do from goods we use now but pay for later.